The real XJ615 was written off 24 June 1964. It was with ETPS at Farnborough when it struck trees on high ground in lifting fog 1.5 miles SE of Haslemere, Surrey. The engine had flamed out following a fuel transfer failure and subsequent mismanagement of boost pump switches.
The French pilot (Capt M Bigois, student on No.23 FW course) was killed.
My guess is that this must have been close to your time at Farnborough, Milt?